The estimated prevalence of short bowel syndrome (SBS) patients with non-malignant disease requiring home parenteral nutrition (HPN) is at least 40 per million of the U.S. population. SBS usually results from surgical resection of some or most of the small intestine for conditions such as Crohn's disease, mesenteric infarction, volvulus, trauma, congenital anomalies, and multiple strictures due to adhesions or radiation. Surgical resection may also include resection of all or part of the colon. SBS patients suffer from malabsorption that may lead to malnutrition, dehydration and weight loss. Some patients can maintain their protein and energy balance through hyperphagia; more rarely they can sustain fluid and electrolyte requirements to become independent from parenteral fluid.
Although long-term parenteral nutrition (PN) is lifesaving in patients with intestinal failure, it is expensive, impairs quality of life and is associated with serious complications such as catheter sepsis, venous occlusions and liver failure. Treatments that amplify absolute intestinal absorption, and eliminate or minimize the need for PN have great potential significance to SBS patients.
The endogenous meal-stimulated hormone, glucagon-like peptide-2 (GLP-2), raises considerable interest for SBS patients. GLP-2 functions to slow gastric emptying, reduce gastric secretions, increase intestinal blood-flow and stimulate growth of the small and large intestine. In animal studies, GLP-2 administration induces mucosal epithelial proliferation in the stomach and small and large intestine by stimulation of crypt cell proliferation and inhibition of enterocyte apoptosis.
SBS patients with end-jejunostomy and no colon have low basal GLP-2 levels and limited meal-stimulated GLP-2 secretion due to removal of GLP-2 secreting L-cells, which are located primarily in the terminal ileum and colon. This GLP-2 deficiency results in a minimal adaptive response following resection and could explain the gastric hypersecretion, rapid intestinal transit and lack of intestinal adaptation observed in these SBS patients.
Jeppesen et al. (Gastroenterology 2001; 120:806-815) have described positive benefit in an open-label study using pharmacologic doses of native GLP-2 in SBS jejunostomy patients. There was significant improvement in intestinal wet weight absorption and a more modest improvement in energy absorption that led to an increase in body weight, lean body mass and a rise in urinary creatinine excretion.
In contrast, SBS patients with colon-in-continuity have elevated basal endogenous GLP-2 levels resulting in an adaptive response to resection characterized by improved wet weight gain and energy absorption. The potential for added benefit of pharmacologic doses of GLP-2 receptor agonists in these patients is not obvious and has not been studied.